531 



rigorous test showing irrefragably that the others must be wrong 

 and tliis alone right ? Evidently where such contradictory opinions 

 have been formed by so many competent judges, we ought, before 

 deciding in favour of one of them, to have a clearness of demon- 

 stration much exceeding that required in any ordinary case. Let 

 us see whether Professor Owen supplies us with any such clearness 

 of demonstration. 



To bring the iirst or occipital segment of the skull into corre- 

 spondence with the " ideal typical vertebra," Professor Owen argues, 

 in the case of the fish, that the parapophyses are displaced, and 

 wedged between the neurapophyses and the_ neural spine — removed 

 from the hsemal arch and built into the upper part of the neural 

 ai-ch. Further, he considers that the pleurapophyses are teleologi- 

 cally compound. And then, in all the higher vertebrata, he alleges 

 that the hasmal arch is separated from its centrum, taken to a dis- 

 tance, and transformed into the scapular arch. Add to which, he 

 says that in mammals the displaced parapophyses are mere processes 

 of the neurapophyses (p. 133) : these vertebral elements, typically 

 belonging to the lower part of the centrum, and in nearly all cases 

 confluent with it, are not only removed to the far ends of elements 

 placed above the centrum, but have become exogenous parts of them ! 



Conformity of the second or parietal segment of the cranium with 

 the pattern-vertebra, is produced thus : — The petrosals are excluded 

 as being partially-ossified sense-capsules, not forming parts of the 

 true vertebral system, but belonging to the " splanchno-skeleton." 

 A centrum is artificially obtained by sawing in two the bone which 

 serves in common as centrum to this and the preceding segment ; and 

 this though it is admitted that in fishes, where their individualities 

 ought to be best seen, these two hypothetical centrums are not 

 simply coalescent, but connate. Next, a similar arbitrary bisection 

 is made of certain elements of the haemal arches. And then, " the 

 principle of vegetative repetition is still more manifest in this arch 

 than in the occipital one :" each pleurapophysis is double ; each 

 hjEmapophysis is double ; and the hsemal spine consists of six pieces ! 



The interpretation of the third and fourth segments being of the 

 same general character, need not be detailed. The only point 

 calling for remark being, that in addition to the above various 

 mcd.is of getting over anomalies, we find certain bones referred to 

 the derma-skeleton. 



Now it seems to us, that even supposing no antagonist interpre- 

 tations had been given, an hypothesis reconcilable with the facts 

 only by the aid of so many questionable devices, could not be con- 

 sidered satisfactory ; and that when, as in this case, various com- 

 parative anatomists have contended for other interpretations, the 

 character of this one is certainly not of a kind to warrant the re- 

 jection of the others in its favour ; but rather of a kind to raak( 



